1. Field
The present disclosure relates generally to manufacturing and, in particular, to a method and apparatus for performing drilling operations. Still more particularly, the present disclosure relates to a method and apparatus for performing drilling operations using air-powered drills.
2. Background
In manufacturing aircraft, the structures and substructures of an aircraft may be constructed by assembling and attaching parts to each other. Structural parts such as, for example, without limitation, spars, ribs, and other suitable structures may be assembled to form wings, a fuselage, stabilizers, and other suitable structures for an aircraft. The different parts are often assembled using fasteners or other similar types of connecting mechanisms. In fastening one part to another part, holes may be drilled through those parts. Fasteners are placed through the holes to secure the parts to each other. For example, holes may be drilled through a spar and a skin panel. The skin panel may then be attached to the spar using fasteners. Thousands of holes may be drilled during the process of manufacturing an aircraft.
These operations may be performed using a drill. A drill is a tool with a rotating bit for drilling holes in various materials. A drill may be powered in a number of different ways. For example, a drill may be powered using an electric motor or an air motor.
In drilling holes during manufacturing of an aircraft, air-powered drills are often used. An air-powered drill is designed to operate at one speed. Reducing and/or controlling drill speed by partially engaging the trigger of the drill is difficult. Further, partial engagement of the trigger is not allowed by current aircraft manufacturing specifications. If an application requires a different speed for drilling a hole, then a different drill motor may be used or the speed of the air drill may be changed by changing the gear system for the drill.
Changing the output gear ratio in the gear system or the spindle system cannot be performed during the drilling process. This change may be performed between drilling operations. Although changing the gear system allows for changing the speed of the air-powered drill, this process may be time consuming and limited in application. For example, as the drill feed rate is varied or as the drill enters or exits the material, the torque load experienced by the drill also varies. This variation in torque and subsequent variation in speed may be undesirable when working with some materials.
Another solution is to use a mechanical governor with spinning weights and springs. To change speeds, the gears and/or weights and springs in this assembly are changed. This type of mechanism can be used to maintain a constant speed under varying torque loads. This type of mechanism cannot be changed during drilling operations. Thus, the time needed to perform multiple drilling operations may be increased by the time needed to change the speed of the air-powered drill.
Thus, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.